System of distribution.



E. THOMSON.

SYSTEM OF DISTRIBUTION.

APPLICATION FILED AUG. 4, 1911.

1,1 05,71 6. Patented Aug. 4, 1911 fm/ /%u E/ihu Thomson,

///'3 9322250 rngg.

UNITED STATES PATENT OFFICE.

ELIHU THOMSON, OF SWAMPSCOTT, JVIASS'ACHUSETTS, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

SYSTEM OF DISTRIBUTION.

Specification of Letters Patent.

Patented Aug. 4:, 1914.

Application filed August 4, 1911 Serial No. 642,371.

To all whom it may concern Be it known that I, ELIHU THOMSON, a citizen .of the United States, residing at Swampscott, county of Essex, State of Massachusetts, have invented certain new and useful Improvements in Systems of Distribution, of which the following is a specification.

My invention relates to systems of distribution, particularly for lighting, and has special reference to those cases in which a flat rate is charged for power with a restriction as to the maximum amount of current to be consumed.

My invention has for its object the-provision of a novel current limiting device for preventing the satisfactory operation of an electric installation when the maximum amount of current allowed by the consumers contract is exceeded.

,The device of my inventionis applicable to alternating current circuits only and is particularly advantageous on local circuits each having its own transformer through which energy is supplied from the main circuit.

I accomplish the desired result of pro ducing a reduction in voltage in the local circuit when the current therein exceeds a predetermined amount, by providing a pair of coils, through which passes the energy from the main circuit to the local circuit, and which are normally in close, mutually inductive, relation, but which when traversed by current exert a repulsive force on each other and are relatively movable so as to separate when the current in them exceeds a predetermined amount. Vhen the coils are in their normal position they introduce but little reactance into the circuit but when they move apart each coil has considerable leakage flux which increases its reactance and reduces the voltage in the local circuit. These two coils may advantageously be made the primary and secondary of a transformer, particularly if the system is one in which each local circuit has its own transformer through which it receives its energy from the main circuit.

My invention will best be understood by reference to the accompanying drawing which shows diagrammatically a system of distribution arranged in accordance with my inventlon.

In the drawing, A represents the main supply circuit of approximately constant potential and B the local circuit, such as a lamp circuit in a house, containing the lamps or othertranslating devices 6 designed for operation on constant potential.

C represents a transformer core carrying the primary winding D connected to the'supply circuit. and the secondary winding" E connected to the local circuit. The secondary winding is movable axially within the primary winding. Its normal position is at the extreme bottom of its travel, slightly beloW the position in which it is shown in the drawing. \Vhen it is in its normal position the two windings D and E are in close, mutually inductive, relation, like the coils of anytransformer with good regulation, but when the coil E moves to a. higher position both coils have considerable leakage flux. which, as is well understood in the art, produccs the same result as reactance in series with the windings; that is, it lowers the voltage of the local circuit B. The coil E is carried by suitable pivot-ed members F, one on each side of the core, and the weight of the coil is partly compensated for by a tension springG acting on the other end of each of the members F. The primary coil D has an L-shaped cross section. The obj ect of shaping the coil thus is to bring a portion of the primary turns below the secondary coil so as to produce a repulsive force between the coils acting in an axial direction when the-coils are traversed by current while at the same time permitting thecoils to lie in close, mutually inductive, relation in normal operation. The .core C has three legs with the 'coils surrounding its middle leg. The outer le 's extend inward above the primary coil F so as to increase the leakage flux of the coil E when it is in its raised position.

The operation of the system will be obvious from the foregoing description. Normally the coil E remains in its lowest position in close, mutually inductive, relation to the primary coil D, so that normal voltage is maintained on the lamps b. When too many lamps are turned on so that the ourrent exceeds a predetermined amount, the repulsive force between the two transformer coils acts to raise the secondary coil E and produce a leakage reactance ,in the transformer which dims the lamps. To restore the lamps to normal brilliancy it is necessary for the consumer to turn off enough to reduce the current to an amount within the proper limit.

I do not desire to limit myself to the par ticular arrangement and connections shown and described, but contemplate changes within the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. In combination with a main supply circuit of approximately constant potential, a local circuit containing current translating devices designed for operation on constant potential, and a transformer, through which said local circuit is supplied from the main circuit, comprising two windings relatively stationary in normal operation but automatically relatively movable when the load on the transformer exceeds a predetermined amount.

"2. In combination with a main supply circuit of approximately constant potential, a local circuit containing current translating devices designed for operation on constant potential, and a transformer, through which said local circuit is supplied from the main circuit, having its windings normally in close, mutually inductive, relation, but relatively movable under the repulsive effect of currents therein exceeding a predeally displaced wit termined amount, and having supportin means for said windings permittin sai relative movement when the currents 1n said windings exceed predetermined amounts.

3. In combination with a main supply circuit of approximately constant potentlal, a local circuit supplied therefrom containing devices designed for operation on constant potential, a pair of coils through which passes the energy su plied from the main to the local circuit, said coils being normall in close mutual inductive relation but pro ucing a repulsive force on each other when traversed b current, and supporting means for said coi s permitting relative movement of said coils when said repulsive force exceeds a predetermined amount.

4. The combination with a main suppl circuit of approximately constant potentla a local circuit containing current translating devices designed for operation on constant potential, a windin in each of said circuits and in close," mutua 1y inductive relation to each other in normal operation, one of said windings'having a rtion of its turns axirespect to the other Winding, said windings bein relatively movable axially when the repulsion efiect between said windings exceeds a predetermined amount.

In witness whereof, I have hereunto set my hand, this first day of August, 1911.

ELIHU THOMSON. Witnesses:

JOHN A; MCMANUB, J r., Ronnu'r SHAND. 

